Do you make an experience or gain an experience? For example,
I made rewarding volunteering experiences ...
I gained rewarding volunteering experiences ...
Are either acceptable? Is there a finer distinction?
Experience meaning knowledge or skill from doing something is used as an uncountable noun and goes with gain.
Experience meaning something that happens that affects you is used as a countable noun, but that is another situation altogether.
It is not clear what your example sentences mean and it is best to rewrite them.
Gaining experience would be more appropriate in this context. 'Making' an experience has the connotation of creating/crafting an experience, which has a different meaning.